Enhanced dry strength and drainage performance by combining glyoxalated acrylamide-containing polymers with cationic aqueous dispersion polymers

Abstract

A process is disclosed for the production of paper with enhanced dry strength comprising adding to the wet end of a paper machine, (a) a glyoxalated acrylamide-containing polymer and (b) a cationic aqueous dispersion polymer. Guidelines for the properties of the polymers that make this coadditive system effective are established. Polymer properties discussed include molecular weight, cationic charge, polymer composition and functionalization, and relative additive amounts.

The invention claimed is: 
     
       1. A process for the production of paper, board, and cardboard with enhanced dry strength comprising the step of adding to the wet end of a paper machine (a) a glyoxalated acrylamide-containing polymer and (b) a cationic aqueous dispersion polymer, wherein the cationic aqueous dispersion polymer has a molecular weight of 250,000 to 2,500,000 daltons and wherein the ratio of cationic aqueous dispersion polymer to glyoxalated acrylamide-containing polymer is from 1:50 to 10:1. 
     
     
       2. The process according to  claim 1  wherein the cationic aqueous dispersion polymer comprises a dispersant polymer and a discrete phase polymer. 
     
     
       3. The process according to  claim 2  wherein the cationic aqueous dispersion polymer contains a dispersant polymer wherein the dispersant polymer incorporates at least one cationic monomer, wherein the cationic monomer is selected from the group consisting of diallyldimethylammonium chloride (DADMAC), 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylaminoethyl)acrylate, 2-(diethylamino)ethyl methacrylate, 3-(dimethylamino)propyl acrylate, 3-(dimethylamino)propyl methacrylate, 3-(diethylamino)propyl acrylate, 3-(diethylamino)propyl methacrylate, N-[3-(dimethylamino)propyl]acrylamide, N-[3-(dimethylamino)propyl]methacrylamide, N-[3-(diethylamino)propyl]acrylamide, N-[3-(diethylamino)propyl]methacrylamide, [2-(acryloyloxy)ethyl]trimethylammonium chloride, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, [3-(acryloyloxy)propyl]trimethylammonium chloride, [3-(methacryloyloxy)propyl]trimethylammonium chloride, 3-(acrylamidopropyl)trimethylammonium chloride, and 3-(methacrylamidopropyl)trimethylammonium chloride and mixtures thereof. 
     
     
       4. The process according to  claim 3  wherein at least one cationic monomer is selected from the group consisting of diallyldimethylammonium chloride (DADMAC), 3-(acrylamidopropyl)trimethylammonium chloride (APTAC), and 3-(methacrylamidopropyl)trimethylammonium chloride (MAPTAC) and mixtures thereof. 
     
     
       5. The process according to  claim 1  wherein the glyoxalated acrylamide-containing polymer comprises the reaction product of an acrylamide-containing prepolymer and glyoxal, and wherein the acrylamide-containing prepolymer is characterized in that it has a cationic charge of from 2-40 mol % of the total monomer content and a molecular weight of from 1,000 daltons to 250,000 daltons. 
     
     
       6. The process according to  claim 5  wherein the acrylamide-containing prepolymer has a molecular weight of from 3,000 daltons to 75,000 daltons. 
     
     
       7. The process according to  claim 6  wherein the acrylamide-containing prepolymer has a molecular weight of from 5,000 daltons to 50,000 daltons. 
     
     
       8. The process according to  claim 7  wherein the degree of total glyoxal functionalization of the acrylamide moiety in the prepolymer is from 6% to 20%. 
     
     
       9. The process according to  claim 5  wherein the degree of total glyoxal functionalization of the acrylamide moiety in the prepolymer is from 3% to 40%. 
     
     
       10. The process according to  claim 1  wherein the cationic aqueous dispersion polymer contains a discrete phase that comprises the reaction product of acrylamide and at least one cationic monomer, wherein the cationic monomer is selected from the group consisting of diallyldimethylammonium chloride (DADMAC), 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylaminoethyl)acrylate, 2-(diethylamino)ethyl methacrylate, 3-(dimethylamino)propyl acrylate, 3-(dimethylamino)propyl methacrylate, 3-(diethylamino)propyl acrylate, 3-(diethylamino)propyl methacrylate, N-[3-(dimethylamino)propyl]acrylamide, N-[3-(dimethylamino)propyl]methacrylamide, N-[3-(diethylamino)propyl]acrylamide, N-[3-(diethylamino)propyl]methacrylamide, [2-(acryloyloxy)ethyl]trimethylammonium chloride, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, [3-(acryloyloxy)propyl]trimethylammonium chloride, [3-(methacryloyloxy)propyl]trimethylammonium chloride, 3-(acrylamidopropyl)trimethylammonium chloride, and 3-(methacrylamidopropyl)trimethylammonium chloride and mixtures thereof. 
     
     
       11. The process according to  claim 10  wherein the cationic monomer comprises [2-(acryloyloxy)ethyl]trimethylammonium chloride. 
     
     
       12. The process according to  claim 10  wherein the discrete phase polymer comprises from 5 to 60 mol % cationic monomer on a molar basis. 
     
     
       13. The process according to  claim 12  wherein the discrete phase polymer comprises from 9 to 50 mol % cationic monomer on a molar basis. 
     
     
       14. The process according to  claim 1  wherein the cationic aqueous dispersion polymer comprises a brine dispersion. 
     
     
       15. The process according to  claim 1 , wherein the cationic aqueous dispersion polymer and the glyoxalated acrylamide-containing polymer are added to the wet end of a paper machine. 
     
     
       16. The process according to  claim 15 , wherein the total combined amount of active polymer solids of cationic aqueous dispersion polymer and glyoxalated acrylamide-containing polymer is 0.05% to 0.80% on a weight basis of the dry pulp. 
     
     
       17. The process according to  claim 16 , wherein the total amount of cationic aqueous dispersion polymer and glyoxalated acrylamide-containing polymer is from 0.05% to 0.60%. 
     
     
       18. The process according to  claim 15 , wherein the ratio of cationic aqueous dispersion polymer to glyoxalated acrylamide-containing polymer is from 1:10 to 5:1.